core: add System.Binary.Base64Encode(Decode) interops

Part of #1055

pkg/compiler/syscall.go

@@ -9,6 +9,8 @@ type Syscall struct {
 // All lists are sorted, keep 'em this way, please.
 var syscalls = map[string]map[string]Syscall{
 	"binary": {
+		"Base64Decode": {"System.Binary.Base64Decode", false},
+		"Base64Encode": {"System.Binary.Base64Encode", false},
 		"Deserialize":  {"System.Binary.Deserialize", false},
 		"Serialize":    {"System.Binary.Serialize", false},
 	},

pkg/core/interop_neo.go

@@ -2,6 +2,7 @@ package core
 
 import (
 	"bytes"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"sort"
@@ -192,3 +193,22 @@ func runtimeSerialize(_ *interop.Context, v *vm.VM) error {
 func runtimeDeserialize(_ *interop.Context, v *vm.VM) error {
 	return vm.RuntimeDeserialize(v)
 }
+
+// runtimeEncode encodes top stack item into a base64 string.
+func runtimeEncode(_ *interop.Context, v *vm.VM) error {
+	src := v.Estack().Pop().Bytes()
+	result := base64.StdEncoding.EncodeToString(src)
+	v.Estack().PushVal([]byte(result))
+	return nil
+}
+
+// runtimeDecode decodes top stack item from base64 string to byte array.
+func runtimeDecode(_ *interop.Context, v *vm.VM) error {
+	src := string(v.Estack().Pop().Bytes())
+	result, err := base64.StdEncoding.DecodeString(src)
+	if err != nil {
+		return err
+	}
+	v.Estack().PushVal(result)
+	return nil
+}

pkg/core/interop_neo_test.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"encoding/base64"
 	"fmt"
 	"testing"
 
@@ -214,6 +215,39 @@ func TestECDSAVerify(t *testing.T) {
 	})
 }
 
+func TestRuntimeEncode(t *testing.T) {
+	str := []byte("my pretty string")
+	v, ic, bc := createVM(t)
+	defer bc.Close()
+
+	v.Estack().PushVal(str)
+	require.NoError(t, runtimeEncode(ic, v))
+
+	expected := []byte(base64.StdEncoding.EncodeToString(str))
+	actual := v.Estack().Pop().Bytes()
+	require.Equal(t, expected, actual)
+}
+
+func TestRuntimeDecode(t *testing.T) {
+	expected := []byte("my pretty string")
+	str := base64.StdEncoding.EncodeToString(expected)
+	v, ic, bc := createVM(t)
+	defer bc.Close()
+
+	t.Run("positive", func(t *testing.T) {
+		v.Estack().PushVal(str)
+		require.NoError(t, runtimeDecode(ic, v))
+
+		actual := v.Estack().Pop().Bytes()
+		require.Equal(t, expected, actual)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		v.Estack().PushVal(str + "%")
+		require.Error(t, runtimeDecode(ic, v))
+	})
+}
+
 // Helper functions to create VM, InteropContext, TX, Account, Contract.
 
 func createVM(t *testing.T) (*vm.VM, *interop.Context, *Blockchain) {

pkg/core/interops.go

@@ -69,6 +69,8 @@ func getInteropFromSlice(ic *interop.Context, slice []interop.Function) func(uin
 
 // All lists are sorted, keep 'em this way, please.
 var systemInterops = []interop.Function{
+	{Name: "System.Binary.Base64Decode", Func: runtimeDecode, Price: 100000},
+	{Name: "System.Binary.Base64Encode", Func: runtimeEncode, Price: 100000},
 	{Name: "System.Binary.Deserialize", Func: runtimeDeserialize, Price: 500000},
 	{Name: "System.Binary.Serialize", Func: runtimeSerialize, Price: 100000},
 	{Name: "System.Blockchain.GetBlock", Func: bcGetBlock, Price: 2500000,

pkg/interop/binary/binary.go

@@ -16,3 +16,15 @@ func Serialize(item interface{}) []byte {
 func Deserialize(b []byte) interface{} {
 	return nil
 }
+
+// Base64Encode encodes given byte slice into a base64 string and returns byte
+// representation of this string. It uses `System.Binary.Base64Encode` interop.
+func Base64Encode(b []byte) []byte {
+	return nil
+}
+
+// Base64Decode decodes given base64 string represented as a byte slice into
+// byte slice. It uses `System.Binary.Base64Decode` interop.
+func Base64Decode(b []byte) []byte {
+	return nil
+}